Extended winglet with load balancing characteristics

Abstract

A winglet and methods of operating an aircraft using the winglet. In some embodiments, the winglet can be mounted to the wingtip of an aircraft and has three segments or portions, namely, a mounting portion, an upwardly extending portion, and a reverse portion, or a portion that extends in an inboard direction.

What is claimed is: 
     
         1 . A winglet attachable to an aircraft wing, the winglet comprising:
 a mounting segment;   an upwardly extending segment; and   a reverse segment, the reverse segment extending a lifting surface of the winglet beyond an end portion of the upwardly extending segment and being configured to produce downward lift.   
     
     
         2 . The winglet of  claim 1  wherein among the mounting segment, upwardly extending segment and reverse segment, only the reverse segment is configured to produce downward lift. 
     
     
         3 . The winglet of  claim 1  wherein a surface of the reverse segment extends in an inboard direction away from the upwardly extending segment. 
     
     
         4 . The winglet of  claim 3  wherein a surface of the reverse segment is configured to be disposed in approximately parallel alignment with a wing of an aircraft to which the winglet is mounted. 
     
     
         5 . The winglet of  claim 4  wherein an inboard portion of the reverse segment extends inwardly at an inclined angle of about five degrees from horizontal. 
     
     
         6 . The winglet of  claim 1  wherein a chord length of the reverse segment is smaller than a chord length of the upwardly extending segment. 
     
     
         7 . The winglet of  claim 1  wherein a leading edge of the reserve segment is sloped aft. 
     
     
         8 . A method of operating an aircraft comprising:
 attaching a winglet to a wing of the aircraft, the winglet having a reverse segment that extends a lifting surface of the winglet past an end portion of an upwardly extending segment of the winglet;   generating upward lift using the at least one wing and at least a portion of the at least one winglet; and   simultaneously generating downward lift using at least a portion of the reverse segment of the winglet.   
     
     
         9 . The method of  claim 8  wherein the upwardly extending segment cants outward from the wing at an angle of about twenty-five degrees from vertical. 
     
     
         10 . The method of  claim 8  wherein the reverse segment extends in an inboard direction away from the upwardly extending segment of the winglet. 
     
     
         11 . The method of  claim 10  wherein the reverse segment has a leading edge that slopes aft from a point nearest the upwardly extending segment to a point near an inboard end portion of the reverse segment. 
     
     
         12 . The method of  claim 11  wherein the angle of the slope is about fifty degrees from lateral. 
     
     
         13 . The method of  claim 8  wherein an airfoil section of the reverse segment has a negative camber. 
     
     
         14 . An aircraft wing having a winglet mounted to an outboard tip of the wing, the winglet comprising:
 a first portion that extends generally horizontally outward from a tip of the wing;   a second portion that extends generally upward at an outward angle of cant; and   a third portion having a contour selected to generally produce downward lift.   
     
     
         15 . The aircraft wing of  claim 14  wherein the contour of the first portion is selected to generally produce upward lift. 
     
     
         16 . The aircraft wing of  claim 14  wherein airfoil sections in each of the first, second and third portions of the winglet are asymmetric. 
     
     
         17 . The aircraft wing of  claim 16  wherein the third portion comprises a negative camber and the first portion comprises a positive camber. 
     
     
         18 . The aircraft wing of the  claim 14  wherein the third portion comprises a sloped leading edge. 
     
     
         19 . The aircraft wing of  claim 14  wherein a chord length of an airfoil section of the third portion is less than all chord lengths of the second portion. 
     
     
         20 . The aircraft wing of  claim 14  wherein a chord length of an airfoil section of the second portion is less than all chord lengths of the first portion.